CVE-2017-9900 in XnView Classic
Summary
by MITRE
XnView Classic for Windows Version 2.40 allows remote attackers to execute code via a crafted .fpx file, related to "Data from Faulting Address controls Code Flow starting at Xfpx!gffGetFormatInfo+0x000000000002e385."
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Analysis
by VulDB Data Team • 10/23/2019
CVE-2017-9900 represents a critical buffer overflow vulnerability affecting XnView Classic for Windows version 2.40 that enables remote code execution through maliciously crafted .fpx files. This vulnerability resides in the Xfpx!gffGetFormatInfo function at offset 0x000000000002e385, where faulty address data controls code flow, creating an exploitable condition that can be leveraged by remote attackers. The flaw manifests when the application processes specially crafted .fpx files that contain malformed data structures, leading to memory corruption that can be manipulated to redirect program execution. The vulnerability is classified as a buffer overflow under CWE-121, which occurs when insufficient bounds checking allows data to overwrite adjacent memory locations, and represents a direct pathway for privilege escalation attacks. This issue demonstrates a classic stack-based buffer overflow scenario where attacker-controlled data is copied into a fixed-size buffer without proper validation, causing the stack to be overwritten with malicious code. The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with the capability to gain unauthorized access to affected systems, potentially leading to complete system compromise and persistent backdoor access. The vulnerability affects systems running XnView Classic 2.40 on Windows platforms, where the application's image processing engine fails to properly validate input data from .fpx files, creating a pathway for attackers to inject and execute arbitrary code with the privileges of the affected application. This represents a significant concern for enterprise environments where image viewing applications are commonly used and may be exposed to untrusted file inputs from external sources or web applications. The vulnerability's exploitation requires a remote attacker to deliver a malicious .fpx file to a victim who has XnView Classic installed, making it particularly dangerous in web-based attack scenarios where users might unknowingly download and open infected files. The root cause of this vulnerability aligns with ATT&CK technique T1203, which involves gaining access to systems through exploitation of software vulnerabilities, and specifically demonstrates how improper input validation can lead to arbitrary code execution in image processing applications. Organizations should consider implementing strict file validation policies, network segmentation to limit exposure, and regular security updates to mitigate the risk of exploitation. The vulnerability also highlights the importance of secure coding practices such as bounds checking, input validation, and proper memory management in multimedia processing applications that handle user-supplied data. Security researchers have documented similar vulnerabilities in image processing libraries where insufficient validation of file headers and metadata can lead to similar exploitation vectors, emphasizing the need for comprehensive security reviews of multimedia handling components in software applications.
This vulnerability demonstrates the critical importance of proper memory management and input validation in multimedia processing applications, particularly those that handle complex file formats like .fpx which contain extensive metadata and structured data. The flaw in XnView Classic's handling of .fpx files illustrates how seemingly benign image processing functionality can become a gateway for sophisticated attacks when proper security measures are absent. The specific location of the vulnerability in the gffGetFormatInfo function indicates that the application's format detection and parsing logic lacks adequate boundary checking, allowing attacker-controlled data to overwrite critical program memory. This represents a fundamental breakdown in the application's defensive measures against malformed input, as the software fails to implement proper bounds checking mechanisms that would prevent buffer overflows from occurring. The vulnerability's remote exploitability makes it particularly dangerous because it can be triggered without requiring physical access to the target system, enabling attackers to execute code from any location where the vulnerable application is installed. The impact of successful exploitation extends beyond simple code execution to include potential privilege escalation, data theft, and persistent system compromise, making this vulnerability a significant threat to enterprise security infrastructure. Organizations should prioritize immediate patching of this vulnerability, as the attack surface is broad and includes any system that processes .fpx files through XnView Classic, with particular concern for web applications that might serve these files to users. The vulnerability also underscores the necessity of implementing defense-in-depth strategies including application whitelisting, network-based intrusion detection systems, and regular security assessments of multimedia processing components within software applications. From a compliance perspective, this vulnerability may trigger requirements under security frameworks such as pci dss, iso 27001, and nist cybersecurity framework, which mandate proper input validation and memory protection mechanisms in applications handling untrusted data inputs. The exploitation of this vulnerability aligns with ATT&CK tactics that focus on initial access and execution, demonstrating how attackers can leverage common software applications to establish footholds within target environments.